This invention relates to clear paint compositions for motorcars, which are capable of forming coatings excelling in resistance to mars caused by car-washing machines and scratch resistance.
Heretofore, means for prevention of mars on motorcar bodies incurred by car-washing machines or of scratches around their keyholes have been in demand. The demand for improvement in that aspect is still intensified recently, from car users who place great importance on appearance. This made it an important task for car makers to develop motorcars with a coating excelling in resistance properties to xe2x80x9cmars caused by car-washing machinesxe2x80x9d and xe2x80x9cscratchingxe2x80x9d, to increase market value of their cars.
Whereas, a coating for cars must exhibit, concurrently with resistance properties to mars incurred with car-washing machines and to scratches around keyholes, many coating performances such as impact resistance, weatherability, finished appearance, adherability and the like. A coating satisfying all of those requirements cannot be obtained by simply relying on technologies for softening or hardening the coating film, and makers take great pains in developing well balanced clear paint compositions for motorcars, which will provide coatings satisfying all of the multi-performance requirements.
We have engaged in concentrative studies with the view to develop a well balanced clear paint composition for motorcars, which improves resistance to mars incurred by car-washing machines and resistance to scratches, and concurrently exhibits favorable performances in finished appearance and storage stability as paint, and come to discover that the above object could be accomplished by a clear paint composition for motorcars, which composition comprises polyester resin containing units derived from alicyclic polybasic acid and/or alicyclic polyhydric alcohol, polyisocyanate compound and rheology-controlling agent and forms a coating having Universal Hardness (HU) not higher than 500 N/mm2 and preferably an indentation depth creep (I) at 0.4 mN load as measured by the method specified in the specification of at least 0.5 xcexcm. The present invention is whereupon completed.
Hei 5 (1993)-263044A-JP has disclosed a paint for plastic parts of a motorcar, which paint comprises a polyester resin formed from use of a polybasic acid having an alicyclic structure and/or polyhydric alcohol having an alicyclic structure, and polyisocyanate compound and which is capable of forming a coating of improved soiling resistance without degradation in the coating performance such as impact resistance and bending resistance. This earlier publication, however, nowhere refers to Universal Hardness (HU) of the coating formed.
Thus, the present invention provides a clear paint composition for motorcars, which is characterized by comprising
Hereinafter the clear paint composition for motorcars of the present invention (xe2x80x9cpresent paint compositionxe2x80x9d) is explained in further details.